To correctly measure a trampoline spring, you must first remove the spring from the trampoline frame to ensure it is in a completely relaxed, unstretched state. Place the loose spring on a flat surface and measure the total length from the outer tip of one hook to the outer tip of the opposite hook (Hook-to-Hook). It is critical that you include both hooks in your measurement and do not measure just the coiled body. Never measure a spring while it is still attached to the trampoline mat or frame, as the tension will stretch the metal and result in an inaccurate reading that leads to purchasing the wrong size replacement.

Step 1: Disassemble The Spring To Restore Its Natural State

The first and most critical step is to completely “relax” the spring. When the spring is installed on the trampoline, it is always under force. Even if your trampoline looks old or the jumping mat is flabby, the spring on it is still stretched beyond its original natural resting length.

• Operation suggestion: find a professional spring hook (T-hook). If there is no such thing, use a strong vise to safely remove the spring from the frame and washer.
• Result: Only when removed will the spring retract to its true, unstretched size. This is the only state where you can get accurate data.
  

Step 2: Place Correctly On The Plane

After the spring is removed, don’t pinch it in your hand to measure it. Handheld measurements are difficult to maintain horizontal, and a slight tilt angle will distort the measurement results.

• Placement: Place the spring flat on a table, workbench or flat ground.
• Check: Make sure the spring is lying straight and not bent. This seemingly redundant action is actually to prepare for the next accurate “hook-to-hook” data, which is the only basis for you to order replacement parts.

Step 3: Measure The Total Length Of “Hook To Hook”

When learning how to measure the trampoline spring, the most common misunderstanding is that only the metal part (spring body) rolled up in the middle is important. All replacement springs are classified and sold by total length. To get the correct number, follow these steps:

Take out your tape measure or ruler.
Align the “0” tick mark with the outermost tip of the left hook. Measure all the way to the outermost tip of the right hook.
Do not stop where the spiral coil ends. Do not measure the inside of the hook.
What you need is the full length of the entire hardware from start to finish.
For example, if the middle coil part is 5 inches, but the total length of the hook is 7 inches, then you have to buy a 7-inch spring instead of a 5-inch one when you place an order.

Do Not Measure The Springs Suspended Above

Most of the time, in order to save some time, you may directly take the tape measure and draw on the spring that has not yet been removed. Measuring an installed spring will cause you to buy the wrong size almost 100%.

• The scientific principle of tension: the hanging spring is stretched to produce rebound. A 7-inch spring, when hung on the frame and stressed, the reading may become 8 inches or even 9 inches.
• Consequences: If you place an order by the stretched length (such as 9 inches), the new spring you buy will be too long. It doesn’t provide any pulling force at all, your trampoline mat will become loose, you can’t jump at all, and there will even be safety hazards.

Author: Fill

As a trampoline safety and maintenance specialist, I focus on helping owners find the exact replacement parts they need. I believe that accurate measurements—starting with a fully relaxed spring—are the foundation of a safe and bouncy trampoline.